The present invention relates to an inertia locking system, in which a latch is biased by a torsion coil spring and adapted to be operated by an inertia force that is applied to the latch against an action of the torsion coil spring when a locked member is brought into contact with the latch member, whereby the latch catches and holds the locked member, and relates to an improvement of a collapsible seat provided with the inertia locking system.
In general, as a seat for a station wagon or the like, there is a seat as shown in FIG. 7. The station wagon has a vehicle body floor F which has a lower step portion f1 and an upper step portion f2. The seat comprises a seat cushion 1 having a substantially C-shaped leg portion 1a provided at a lower portion thereof which is close to a front side of the seat cushion 1, the C-shaped leg portion 1a being mounted to the seat cushion 1 with an opening of the leg portion 1a facing upwardly, and a seat back 2 pivotally supported to the upper step portion f2 so as to be tillable. More particularly, the seat back 2 is provided with a bracket 2a which protrudes downwardly from a lower portion of the seat back 2, and the seat back 2 is pivotally supported to the upper step portion f2 by causing the bracket 2a to be pivotally supported to the upper step portion f2 by means of a supporting shaft 2b. The seat cushion 1 has a curved arm 1b extending rearward from a rear portion of the seat cushion 1. The seat cushion 1 pivotally supported to the seat back 2 by causing the curved arm 1b to be supported to a lower portion of a side of the seat back 2 by means of a supporting shaft 1c. The seat cushion 1 can be jump up or rotated around the supporting shaft 1c. 
The leg portion 1a has a lower section 1axe2x80x2 and is adapted to be received at the lower section 1axe2x80x2 thereof in a receiving port of an inertia locking system 3 mounted on the lower step portion f1 of the vehicle body floor F.
Referring now to FIG. 8, the conventional inertia locking system 3 will be discussed hereinafter in order to facilitate understanding of the present invention. The inertia locking system 3 comprises a pedestal 31 mounted on the lower step portion f1 of the vehicle body floor F, the pedestal 31 having a substantially U-shaped receiving port 30 for receiving the lower section 1axe2x80x2 of the leg portion 1a, and a latch 32 formed into a substantially inverted J-shape for catching the lower section 1axe2x80x2 of the leg portion 1a. The receiving port 30 is open toward an obliquely upper direction and adapted to receive the lower section 1axe2x80x2 of the leg portion 1a. The latch 32 has a lower base portion 32a, a curved upper portion, and a curved surface between the lower base portion 32a and the upper portion 32b. The latch 32 is pivotally supported at the lower base portion 32a thereof to a side portion of the pedestal 31 by a pivot pin 33 with the curved upper portion 32b thereof facing the receiving port 30. The inertia locking system 3 further includes a torsion coil spring 34 biasing the latch 32 rearward away from the receiving port 30.
A coiled portion 34a of the torsion coil spring 34 is mounted on an axis of the pivot pin 33. One end 34b of the torsion coil spring 34 is fastened to a projection piece 35 which projects laterally from the side portion of the pedestal 31 at a position which is close to a rear side of the pivot pin 33. The other end of 34c of the torsion coil spring 34 is fastened to a projection piece 36 protruding laterally at a side portion of the latch 32 which is above the pivot pin 33.
In the inertia locking system, the latch is always biased rearward away from the receiving port 30 of the pedestal 31 by the torsion coil spring 34 in order to dissolve a troublesome operation which a passenger is forced to carry out when releasing the seat from a locked condition of the seat by the latch system 3. The seat is adapted to be engaged through the leg portion 1a thereof with the inertia locking system in a condition as shown in FIG. 8. That is, the seat is engaged with the inertia locking system in a state where the lower section 1axe2x80x2 of the leg portion 1a is received in the receiving port 30. In this condition, the lower section 1axe2x80x2 of the leg portion 1a is not gripped and held by the latch 32 yet. When car-collision or the like occurs, an inertia force will be applied to the latch 32 and the latch 32 is operated against an action of the torsion coil spring 34 by the inertia force in such a manner that a position of center of gravity which corresponds to a fastening point of the spring end 34c is moved to a front side. Thus, the lower section 1axe2x80x2 of the leg portion 1a which is received in the receiving port 30 of the pedestal 31 can be gripped and held by the latch 32.
However, in the seat which can be jumped up as described above, since an offset exists between a center of rotation about the supporting shaft 1c (FIG. 7) and the center of gravity of the seat cushion 1, a rotational force which tends to cause the seat cushion 1 to be jumped up is generated at a time when a sitting person does not exist due to the car-collision or the like. In the inertia locking system, since the latch 32 is operated after the inertia force is generated due to the collision or the like, considerable time is required until the latch 32 engages with the lower section 1axe2x80x2 of the leg portion 1a of the seat cushion 1, so that there is a possibility that the lower section 1axe2x80x2 of the leg portion 1a will not be gripped and held by the latch 32.
Further, since the latch 32 is always biased rearward away from the back of the receiving port 30 of the pedestal 31 by the torsion coil spring 34, if any foreign materials and the like adhere around an axis of the pivot pin 33, the passenger can not know in advance that the latch 32 is in a non-rotatable state due to the foreign materials and the like.
It is an object of this invention to provide an inertia locking system which can securely lock a vehicle seat relative to a body floor of a vehicle by a simple operation. It is another object of the present invention to provide a collapsible seat in which, when car-collision or the like accidentally occurs, a seat cushion can be securely prevented from being jumped.
In accordance with one aspect of the present invention, there is provided an inertia locking system for locking a vehicle seat relative to a body floor of a vehicle, which is adapted to be arranged on the body floor of the vehicle. The vehicle seat includes a seat back supported to the vehicle body floor and a seat cushion pivotally supported to the seat back. The seat cushion has a substantially C-shaped leg portion attached thereto with an opening thereof facing upwardly. The leg portion has a lower section. The inertia locking system comprises a pedestal adapted to be mounted on the body floor and having a substantially U-shaped receiving port, the receiving port having a first obliquely, upward facing opening for receiving the lower section of the leg portion, a substantially U-shaped clip having a second opening for receiving the lower section of said leg portion, the clip being received in the first opening of the receiving port and attached to the pedestal with the second opening thereof facing obliquely and upwardly, the second opening of the clip having a width slightly narrower than a diameter of an axis of the lower section of the leg portion, a latch formed into a substantially inverted J-shape, the latch having a lower base portion, a curved upper portion, and a jaw portion protruding from the lower base portion, the latch being pivotally supported at the lower base portion thereof to a side portion of the pedestal by a pivot pin with the upper portion thereof facing the receiving port and with the jaw portion protruding beyond an inner surface of the receiving port, and a torsion coil spring for always biasing the latch away rearward from the receiving port, the torsion coil spring having a coiled spring portion and first and second ends, the coiled spring portion being mounted on an axis of said pivot pin, the first end of the torsion coil spring being fastened to a position of the side portion of the pedestal which is close to a rear side of the pivot pin, the second end of the torsion coil spring being fastened to a side of the latch, wherein when the lower section of the leg portion is received in the first opening of the receiving port and the second opening of the clip, the lower section of the leg portion kicks the jaw portion so as to rotate the latch in the opposite direction to the direction in which the latch is always biased by the torsion spring, whereby the lower section of the leg portion is positively caught by the upper curved portion of the latch.
According to a further aspect of the present invention, there is provided a collapsible seat for a vehicle. The seat comprises a seat back supported to a body floor of a vehicle, a seat cushion pivotally supported to the seat back so as to be tillable, the seat back being provided with a substantially C-shaped leg portion, the leg portion being attached to the seat cushion with an opening thereof facing upwardly; the leg portion having a lower section, and an inertia locking system for locking the seat relative to the body floor. The inertia locking system comprises a pedestal mounted on the body floor and having a substantially U-shaped receiving port, the receiving port having a first obliquely, upward facing opening for receiving the lower section of the leg portion, a substantially U-shaped clip having a second opening for receiving the lower section of the leg portion, the clip being received in the first opening of the receiving port and attached to the pedestal with the second opening thereof facing obliquely and upwardly, the second opening of the clip having a width slightly narrower than a diameter of an axis of the lower section of the leg portion, a latch formed into a substantially inverted J-shape, the latch having a lower base portion, a curved upper portion, and a jaw portion protruding from the lower base portion; the latch being pivotally supported at the lower base portion thereof to a side portion of the pedestal by a pivot pin with the upper portion thereof facing the receiving port and with the jaw portion protruding beyond an inner surface of the receiving port, and a torsion coil spring for always biasing the latch away rearward from the receiving port, the torsion coil spring having a coiled spring portion and first and second ends, the coiled spring portion being mounted on an axis of the pivot pin, the first end of the torsion coil spring being fastened to a position of the side portion of the pedestal which is close to a rear side of the pivot pin, the second end of the torsion coil spring being fastened to a side of the latch, wherein when the lower section of the leg portion is received in the first opening of the receiving port and the second opening of the clip, the lower section of the leg portion kicks the jaw portion so as to rotate said latch in the opposite direction to the direction in which the latch is always biased by the torsion spring, whereby the lower section of the leg portion is positively caught by the upper curved portion of the latch.
The other features than the features mentioned above will be apparent in an embodiment in accordance with the present invention described below.